1. Field of the Invention
The present invention relates to a magnetic recording medium on which a data track pattern and a servo pattern are formed by concave/convex patterns and to a stamper on which a stamper-side concave/convex pattern corresponding to the concave/convex patterns of the magnetic recording medium is formed. The present invention also relates to a recording/reproducing apparatus including a magnetic recording medium, a recording head, and a reproducing head and to a method of measuring a parameter that measures a predetermined parameter for at least one of a recording head and a reproducing head installed in a recording/reproducing apparatus.
2. Description of the Related Art
As one example of a recording/reproducing apparatus that is equipped with this type of magnetic recording medium and can measure a predetermined parameter for at least one of a recording head and a reproducing head, Japanese Laid-Open Patent Publication No. 2005-166115 discloses a hard disk drive apparatus (a “magnetic recording apparatus”) with an offset measuring function. This hard disk drive apparatus includes a discrete track-type hard disk (magnetic recording medium) where non-magnetic regions are formed between tracks in discrete regions, a composite magnetic head including a recording head and a reproducing head, a driving mechanism that moves the magnetic head between the inner periphery and the outer periphery of the hard disk, and a control unit that carries out overall control of the hard disk drive apparatus. The hard disk described above is provided with offset measurement regions that are used for carrying out an offset measuring process and are disposed between the discrete regions (data track pattern regions) for recording recorded data and servo regions (servo pattern regions) in which servo data is recorded. The offset measurement regions are entirely constructed of a magnetic material without non-magnetic regions being formed therein.
During an offset measuring process carried out by this hard disk drive apparatus, offset measurement signals (measurement patterns, hereinafter also referred to simply as “measurement signals”) are written in offset measurement regions on the hard disk in a state where data has not been recorded on the hard disk and the offset measurement regions have been initialized. More specifically, in a state where the reproducing head is being made on-track to an innermost track, for example, measurement signals are written in the offset measurement regions using the recording head. When doing so, in a hard disk drive apparatus of this type, when the magnetic head has been moved toward the inner periphery or the outer periphery of the hard disk, a line that joins the center in the width direction of the recording head and the center in the width direction of the reproducing head (as one example, a line that is parallel to the direction in which the arm extends) is intersected by the center line of a track (i.e., a skew angle is produced). Accordingly, when the reproducing head is being made on-track to a track (i.e., when the center in the width direction of the reproducing head has been aligned with the center in the width direction of a track), the center in the width direction of the recording head will be positioned away from the center of the track, or in other words, the recording head will be made “off-track”. This means that the measurement signals will be recorded at positions that are separated from the center line of the track by a distance corresponding to the extent to which the recording head is made off-track.
Next, by reading the measurement signals using the reproducing head, the center in the radial direction of the regions in which the measurement signals were written, or in other words, a position that matches the center in the width direction of the recording head when the measurement signals were written is specified. More specifically, by moving the reproducing head in the radial direction of the hard disk by increments of a predetermined amount, the measurement signals are read from the offset measurement regions. Here, when the center in the width direction (i.e., the radial direction) of the reproducing head is positioned off the center in the radial direction of the regions where the measurement signals are written toward the inner periphery or the outer periphery, the amplitude of the reproducing signal for the read measurement signal decreases. On the other hand, when the center in the width direction (i.e., the radial direction) of the reproducing head matches the center in the radial direction of the regions where the measurement signals were written, the amplitude of the reproducing signal for the read measurement signal reaches its maximum value. Accordingly, the control unit specifies the center position of the reproducing head at a point where the amplitude of the reproducing signal for the measurement signals reaches its maximum value as the center in the radial direction of the regions in which the measurement signals were written and sets the distance between the specified center and the center of the reproducing head during the writing of the measurement signals (i.e., the center of the track) as the offset of the recording head with respect to the reproducing head, thereby completing the measurement process.